There are several things wrong with the government's plans to pay for higher education with a hypothecated graduate tax – sorry, 'contribution'. For a start, it will be relatively more expensive for less well paid graduates, such as teachers and nurses. But more fundamentally, the entire debate about higher education funding – which seems to have been reduced to an unappealing slugging match between tuition fees in one corner and some kind of graduate tax in the other – now takes it for granted that individual students ought, one way or another, sooner or later, to pay for their own university courses. They get the benefit, so they should pay, right?

But if we're following that logic, why stop at making doctors, for example, pay for their degrees? Why not charge each patient a small fee – sorry, contribution – carefully calculated according to the proportion of the doctor's training that goes towards their diagnosis and treatment? Presumably because even Vince Cable and David Willetts would think that was crazy and unworkable.

Here's another crazy idea. Since, generally speaking, society as a whole benefits from a skilled graduate workforce, why not split the difference and spread the cost of higher education across society as a whole, with everyone paying what they can afford? You could do this using an arcane system that involves levying higher income taxes – sorry, contributions – from higher earners (most of whom, so we're told, are graduates anyway). And just think how much red tape could be cut that way, too.